The present invention relates to airborne radars and more particularly to controllers for airborne radars. Radar is often sequenced through various scans, with each scan or set of scans dedicated to a particular one of the tasks performed by the radar. The scan sequence and the time alloted for each scan type limits the type and number of data gathering tasks the radar can support. In present airborne radars, below 1500 feet above ground level (AGL), the radar executes a four scan cycle. One scan gathers weather data and three scans detect windshear. Even at these current rates, the amount of weather data gathering capability is marginal. Additional data gathering tasks cannot, therefore be added to the radar scan schedule of existing radars without compromising weather radar performance.
Present day airborne radar systems also require that the pilot manually control the tilt angle of the radar antenna. One such example is described in "RDR-4B Forward Looking Windshear/Weather Avoidance Radar System Pilot's Manual with Radar Operating Guidelines", AlliedSignal Aerospace Commercial Avionics Systems, ACS-5082, Rev 1, July 1996 , the entire contents of which are incorporated herein by reference.
The pilot manual describes the procedure for selecting the antenna tilt to scan for weather. This procedure requires the pilot to adjust manually the tilt of the antenna for each range scale until "a sprinkle of ground return" is visible at the far edge of the display. At the larger range scales (&gt;80 nmi) the ground returns may not be visible making an optimal antenna tilt decision difficult due to the lack of terrain returns. At these ranges, it is difficult for the pilot to make a distinction between weather returns and strong ground clutter returns without continually adjusting the antenna tilt to see if the returns disappear as the antenna beam is adjusted upward. As the altitude of the aircraft changes with respect to target height, the antenna tilt angle must be adjusted to maintain the proper positioning of target returns. This requirement increases pilot workload, and presents possible difficulties in maximizing the effectiveness and utility of the radar system.